1. Field of the Invention
The present invention relates to a lead frame package structure, and more particularly, to a lead frame package structure with low electromagnetic interference and low crosstalk.
2. Description of the Prior Art
There are several package types for an integrated circuit (IC) according to different materials of a die holder of the IC, such as lead frame package, laminate substrate package, tape package and ceramic package. Since the lead frame package has low cost and low speed signal transmission, the lead frame package is not suitable for high speed signal transmission interface such as DDR3-1333 Mbps, HDMI or USB3.
Please refer to FIG. 1 to FIG. 3, FIG. 1 is an appearance diagram of a traditional lead frame package structure 10, FIG. 2 is a top view of the lead frame package structure 10, and FIG. 3 is a side view of the lead frame package structure 10. As shown in FIG. 1 and FIG. 2, the lead frame package structure 10 includes a plurality of lead frames 100 and a die 11. The lead frame 100 includes an outer pin 102, an inner pin 104 and a lead 106. The outer pin 102 is electrically connected to a printed circuit board (PCB), which is not shown in FIG. 1 and FIG. 2, the inner pin 104 is electrically connected to die 11 by soldering, e.g. a gold wire 103 shown in FIG. 2, and the lead 106 is connected between the inner pin 102 and the outer pin 104. As shown in FIG. 3, the lead frame package structure 10 further includes a holder 12 for supporting the die 11 and a molding 13 for covering the lead frame 100 and the die 11.
According to above description, the lead frame package structure 10 is not a multi-layer structure to design a reference ground plane as a printed circuit board does, which results in difficult impedance control, signal crosstalk and high loop inductance of a power distribution network (PDN). In order to solve above disadvantages, in the prior art, the lead frame package structure 10 disposes ground lines between each lead frames 100. However, the added ground lines occupy the pins for disposing the lead frames 100, causing a number of signal pin out decrease.